Intermittent hypoxaemia without orthodeoxia due to right-to-left shunting related to an elongated aorta

Anatomical factors triggering platypnea-orthodeoxia in adults

Right to left shunting through a patent foramen ovale (PFO) or atrial septal defect (ASD) can cause platypnea-orthodeoxia even in a setting of normal pulmonary artery pressures. However, the late onset of symptoms despite the congenital origin of the anatomical defects is not well understood. We report a case series of patients presenting with dyspnea and orthodeoxia who developed right to left shunting as a result of associated anatomical changes that occur with aging such as tortuosity and elongation of the aorta. We propose that these acquired anatomical changes can favor right to left shunting in the setting of congenital abnormalities, therefore explaining the late onset of symptoms.

Right-to-left interatrial shunt despite normal pulmonary artery pressure. Anatomical implications

Platypnea-orthodeoxia is a rare syndrome characterized by dyspnea induced by the upright position and relieved by supine position and an arterial deoxygenation increased by the upright position which improves during recumbency. In many cases, this syndrome has been associated with patent foramen ovale and right-to-left shunt. Several anatomical factors that can alter the atrial anatomy and facilitate shunting through an interatrial communication have been related with this syndrome. We present a case in which an enlarged aortic root was the main anatomical factor that contributed to transient right-to-left shunting induced by postural changes.